Timeline: six years of arguments over Heathrow third runway

December 2003 The then transport secretary, Alistair Darling, backs a third runway at Heathrow in the aviation white paper but sets targets on noise and air pollution. "It's essential we plan ahead to meet the pressures we know we'll face as a result of a growing economy," he says.

December 2006 In an update to the white paper, the government reiterates its support for a third runway, despite the environmental agenda. Ministers again cite the economy as a key factor.

August 2007 Protesters set up the Camp for Climate Action near Sipson, on the northern edge of Heathrow.

November 2007 The government launches a public consultation on a third runway including its effect on noise and nitrogen dioxide levels. Ruth Kelly, transport secretary, says the case still stands. "If Heathrow is allowed to become uncompetitive, flights and routes will simply move elsewhere."

September 2008 The Conservatives pledge to scrap a third runway and replace it with a high-speed rail link.

January 2009 The government approves a third runway, to take the number of flights handled by the airport from 480,000 to more than 700,000 a year. It also sets up a company to design a north-south high-speed rail route. The announcement is condemned by opposition MPs, residents and green groups.

• This article was amended on 9 April 2010. In the original, the figures 480,000 and 700,000 were said to be annual passenger figures. This has been corrected.